Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds real value beyond those annotations: the KASI provenance, the freshness timestamp (updated 2026-11-12), the inclusion policy for substitute holidays and election days, and the data coverage limit that implicitly bounds behavior for out-of-range years.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, front-loaded with what the tool returns and followed by coverage facts; nothing is redundant with the title. The parenthetical detail about specific 2026 dates (Labor Day, Constitution Day) is close to trivia for tool selection, but it does inform expected output and is compact enough to keep.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

This is a simple read-only list tool with all three parameters fully documented in the schema and no output schema to explain. The description covers what is returned, where the data comes from, and its validity window, leaving only minor gaps such as result ordering or empty-range behavior.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, and the schema already states the YYYY-MM-DD formats and that year is ignored when from/to are supplied. The description restates the year-or-range choice but adds no format, precedence, or boundary semantics beyond what the schema documents, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb and resource ('List South Korean public holidays (공휴일)') and states the two supported query shapes, year or date range, plus the output trait ('with Korean names'). This clearly separates it from siblings like kr_business_day and kr_add_business_days, which are day-math tools rather than holiday listings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives a usable context boundary by declaring the supported window (2024-2027) and the kinds of days included (substitute holidays, election days, 2026 additions), which tells an agent when results are trustworthy. It stops short of explicitly naming alternatives such as kr_business_day for single-day checks or stating what to do outside the covered years.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.